smith



A. B. SMITH.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION man MAY L0. 1916.

1,308,749. Patented July 1, 1919.

a swans-shin I.

A. B. SMITH.

AUTOMATIC IELEPHONE SYSTEM.

APPLICATION FILED MAY 10. 1915.

1 08,749. Patented J uly 1, 1919.

3 SHEETS-SHEET 2- Fig.5.

Hi 2 01" may A. B. SMITH.

AUTOMATIC TELEPHONE SYSTEM.

APPLICATION men MAYIO. 191s.

Patented July 1, 1919.

3 SHEETS-SHEET 3- UNITED STATES PATENT oEEIcE.

ARTHUR BESSEY SMITH, OF EVANSTON, ILLINOIS, ASSIGNOIR. TO AUTOMATIC. ELECTRIC COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

AUTOMATIC TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented July 1, 1919.

Application filed May 10, 1916. Serial No. 96,493.

' To all whom. it may warn:

Be it known that I, ARTHUR BESS-BY SMITH, a citizen of the United States of America, and a resident of Evanston, county of Cook, and State of Illinois, have invented certain new and useful Improvements in Auton'iatic Telephone Systems, of which the following is a specification.

While my invention relates in general to automatic telephone systems, it is concerned more particularly with methods of automatic calling between widely separated automatic exchanges connected by toll or long distance lines.

It has lon been the common practice, in systems 0 the above general character, to utilize the long distance lines fortele graphic purposes simultaneously with their use telephonically, the telephone connections being established manually in the old and well known manner. Recently it 'has in some instances been considered advisable to provide means whereby the long distance connections could be established automatically between the various exchanges, thereby considerably expediting the service. Such:

to the best of my presoperation, however, I ent-knowledge, has heretofore made 1t necessary to dispense with the telegraph circuits. Y

It is the object of the present invention to provide circuit arrangements and devices whereby long distance'lines arranged with superimposed telegraph circuits are adapted for automatic operation without DBCQSSlfflt ing the elimination of such telegraph circuits. I employ the usual simplex circuit superimposed either on a single line or on which simplex circuit may be used for operating telegraph instruments or any other devices capable of being 0perated by direct current. To operate the automatic switches, I provide at each end' of the above mentioned simplex circuit a branch circuit, the branch at one end containing a relay-and the branch at the other end. containing a source of alternating current. I provide, furthermore, means where ,by the direct and alternating currents are confined to theirrespective circuits at each end,there'by making it possible to telegraph and set up A taneously over the same line;

vice key K an automatic connection simul The particular means employed in attaining the foregoing objects will be set forth and described in detail hereinafter, reference being had to the accompanying drawings, in which Figures 1, 2, and 3, When taken in order withthe lines at the ends thereof in alinemcnt, represent diagrammatically a complete circuitconnection between a calling substation A and a called substation A in a system embodying the principles of my'invention. The said connection has been established through the medium of the cord circuit P, toll line 51-52, repeater E, and connector F.

ferring now to Fig. 1, the substation A may be of any suitable or approved type, and as shown herein consists of the .usual common battery arrangement in which the transmitter and receiver are connected in series. The line conductors 12 and 13 have allotted to them at the exchange the usual line and cut-ofi' relays 14 and 15, the answering jack J, and the lamp signal L.

The cord circuit P likewise may be of any suitable ty e. As shown herein it comprises essential y a bridged relay 21 which, in conjunction with sleeve relay 20, controls the supervisory lamp L; and the ringing up looking relay 22 which, in conjunction with sleeve relay 23, controls the superyisory lamp L. Keys K and K are ringmg keys, while key K is a listening keyadapted, when operated, to bridge theoperators head set across the two strands of the cord circuit.

The toll line 51-52 may be provided at the exchange in whichthe line of substationA terminates with the regular multiple jacks. one of which is shown at J. Associated with the jack J in theusual manner is shown a drop 30 and a cut-off relay 31. The remaining equipment directly associated with jack J has been indicated collectively by the reference character M-and comprises a calling device S, a calling dea switching relay 32, an alternating current generator 48, and what I term a barrier, consisting of the condenser 34 and the reactanoe coil 33. The operation and functions of this apparatus can best be described later in connection with the detailed descriptio of the operation.

It.'may.be mentioned a this time, however.

' 51-52 is provided with a multiple jack J and the associated drop 165 and cut-off relay 166. Relay 160 is an alternatingl current relay so designed and constructe that it will maintain its armature continuously attracted when its windings are traversed by alternating current. The condenser 164 and reactance coil 163 constitute a barrier similar to the one at the other end of the line which has been previously mentioned.

The toll line 51-52 is also provided at the distant exchange with a repeater E to which it is connected through contact springs of the cut-off relay 166. The repeater E may be of the *neral type of repeater disclosed in U. S. etters Patent No. 1,136,912, granted April 20, 1915, to Talbot G. Martin, although the circuits are somewhat modified to enable it to operate in conjunction with the rest of the equipment. The operation and functions of the various relays of the repeater will be described fully hereinafter.

Directly connected with the repeater E is shown a connector switch F (Fig. 3) which may be of the general type of connector switch disclosed in U. S. Letters Patent No. 815,176, granted March 13, 1906, to Keith, Erickson, and Erickson; being, however, more nearly of the particular type disclosed in British patent to the Automatic Telephone Mfg. Co., No. 2270 of 1914. A connector switch of the foregoing general description may be given access to a plurality of subscribers lines and is operable in response to digits of a called number to establish connection with an Y one of the lines to which it has access. t will be understood, of course, that selector switches may be inserted between the repeater E and the connector F in order to increase the capacity of the system. Selectors suitable for this purpose are-shown in the British patent to the Automatic Telephone Mfg. 00., No. 2543 of 1914.

One of the lines accessible to connector F is shown in F ig. 3 as extendin to the substation A', which, as illustrate is an automatic substation of well known ty e. A similar substation is shown and described in Britislf patent to Martin, No. 1419 of 1911).

means The line ofv substation -A' may be rovided at the exchange with an indivi ual lino switch C which shown in Fig. 3 is similar to the line switch shown and described in U. S. Letters Patent No. 1,078,690, granted Jan. 17, 1912, to Frank Newforth. Since line switches of the above type are well known an extended description will not be iven. It will be suflicient to say that tirough the medium of line switch 0 the line of substation A, when calling, is given access to'aqilurality of selector switches, or connector' switches as the case may be, whereby connections may be established with other local lines in well known manner.

Referring now to Figs. 1 and 2, it will be seen that the toll line 51-52 is provided at each end with a repeating coil through the medium of which it is connected inductivcly with the line equipments. The provision of the repeating coils renders possible the formation of a simplex circuit including the two sides of toll line 5152 in parallel. In connection with this simplex circuit 1 have shown diagrammatically a simple Morse telegraph circuit including the battery B, key K and relay coil 80 in Fig. 1, and the relay coil 81, and key K in Fig. 2. The two branch circuits which have been previously mentioned as being essential to my invention ma be clearly seen, one at each end, extending from the junction of the line winding; of the repeating coil to the inductance of the barrier.

For supplying direct current for operating and talking purposes I have shown in each exchange a battery having its positive pole grounded, and in connection with the telegraph circuit 1 have shown an additional battery having its negative pole grounded. Associated with the connector F I have shown a generator Gen for supplying ringng current, an interrupter l for supplying n itcrmittent ringin impulses, and a busy sigfialmg machine 6 aving given a general description of the apparatus, I Wlll now proceed to a more detailed explanation of the operation of the same. For the purposes of this eX- planation it will be assumed that the subscriber at substation A wishes to obtain connection with the subscriber at substation A, this being the completed circuit connection shown in the drawings and previously referred to. Inasmuch, as a great deal of the equipment shown is well known and has been described fully in the publications referred to, the operation of such apparatus will. be described in a more or less general manner.

Upon the removal of the receiver at sub station A to initiate the call a circuit is completed for the line relay 14, thereby light- I E giound at (1 ing the line lamp L. In this manner the attention of the she will respond by inserting plug of cord circuit cuitis thereupon completed includingthe sleeve relay 20 and the cnt-ofi' relay 15, whereby the line relay 14 is disconnected and the lamp L is extinguished. The operator may now throw her listeningkey K and converse with the calling subscriber, obtain ing the usual information regarding the name and number of the party wanted, etc.

In the present case, since thewanted subscriber is located in a distant exchange to which the toll operator has access over the toll line 5152, the operator will insert the calling 'plug of cord circuit P in the jack J the idle or busy condition of the toll line being first determined by testing with the tip of the plug in the regular manner. Upon the insertion of the plug, acircuit is complelcd over the sleev of the jack as follows: winding of cutoff relay 31, sleeve of jack J, sleeve of plug, and winding of relay to battery B. The sleeve relay 23, upon energizing, disconnects the test wire from the upper strand of the cord and connects ground to the armature of supervisory relay 22 of no consequence at this time. however). The cut-ofi' relay 31, upon energizing, disconnects the drop 30 and prepares a locking circuit for relay 32.

, Since the connection is to be established automatically, the operator will now throw the calling device key K, thereby inserting the calling device S in a circuit to be presently described and also closing a circuit for relay as follows: ground at G, contact springs 36 and 35, and winding of relay 32 to battery B. Upon httracting its armature, relay 32 inserts its winding in the following locking circuit: ground at G, contact springs 42 and 41, contact springs 46 and .and winding of relay 32 to battery B.

As a further result of the energization of relay 32, the following circuit is ponipleted the answering to the distant exchange: ground at G, A. C.

generator 48, contact springs 44 and 43, calling device S, contact springs 38 and 37, condenser 34, reactance coil 33, windings 75 and 76 of repeating coil R in parallel, line conductors 51 and 52 in parallel, windings 177 and 178 of repeating coil R actance coil 163, condenser 164, and windings of alternating current relay 160 to ground at G The reactance coils 33 and 163 and the condensers 34 and 164 are of such inductance and capacity, respectively, that the above circuit is resonant to the frequency of generator 48, whereby sufiicient current is permitted to flow to operate the alternating current relay 160. It will boobserved that in addition to the path to ground by way of alternating current relay v160,

operator is attracted and P in the jack J. A cir-. 'native or shunt paths, however,

coils in series therewith. These in parallel, re

possible paths by way of generator 48 might find These altereach include one or more telegraph relays which are of there are two other which current from its way back to ground at G.

such high impedance is to permit very little of the high frequency alternating current to ass The telegraph relays are not afl'ected by what current does leak through them by reason of their comparatively heavy armatures and the adjustment of their retractile springs. I have found it desirable, in order to increase the impedance of the telegraph branches at each end, to insert impedance K coils may be connected as shown in the drawings.

To proceed with the operation, the A. C. relay 160, upon attracting its armature, com; pletes a;circuit including the line relays o repeater E over the following path: ground at G, winding of relay 211, contact springs 168 and 169, winding 1910f repeating coil R armature and contact of A. C. relay 160, winding 190 of repeating coil R contact springs 171 and 170, and winding of relay 210 to battery B". Upon energizing, relay 210 closes a circuit for the slow-acting relay 213 as follows; ground at G, contact springs 217 and 218, and winding of relay 213 to battery B Relay 213 attracts its armature, and by means of contact springs 232, 233, and 234 shifts the sleeve of jack J 2 from its normal connection by way of con-. ductors 170 and 171 to relay 166, to battery B by way of conductor 170' and resistance 239. In this manner a guarding potential is placed on the sleeve of jack J; and, furthermore, should an operator disregard her busy test or plug into jack J accidentally she will not release a connection already established automatically for the cut-oil relay 166 has had its circuit opened as explained. Relay 213 "also prepares, by' means of contact springs 237- and 238, an energizin circuit for relay 214; and, by means 0 contact springs and 236, a locking circuit for relay 212. y Relay 211, upon energizing, closes a circuit for the line relay 250 of the connector F over the following-path: ground at G, lower winding of line relay 250, normally closed' contacts of relay 253, conductor 243, contact springs '220 and 219, contact springs 230 and 231, winding of reactance coil 215,

eonductor240, contact springs 226 and 225,

The operator at the originating exchange may now proceed to dial the wanted number. Upon the operation of the calling de vice S in accordance with the first digit, the impulse springs of the calling device are separated momentarily a number of times, interrupting each time the previously described circuit including; the generator 48 and the A. C. relay 100. As a result of these interrupt-ions of its circuit. relay 160 delinergizes a. corresponi'ling number of times and at each dci ncrgization breaks the circuit of relays 210 and 211 of the repeater E. \Vhcnce it will be seen that relays 216 and 211 will be dei nergized a number of times corresponding to the first digit of the called number.

At the first dei nergization of relay 210. a circuit is completed for the slow acting relay 2H as follows ground atti, contact springs 217 and 216, contact springs 21:18 and 237 and winding of relay 21-lto battery B Relays 213 and 214, being slow acting, retain their armatures in operated position during impulses, after which relay ill retracts its armature. In its energized condition. relay 2H disconnects the conductors 242 and 243 from the conductors 2-H] and 241, respectively, and from the normally bridged coil 21:"): substitutes for the latter a direct. path by way of contact springs 220 and 215) and contact springs 23!) and .229; and completes an initial energizing circuit for rciay 212 as follows: ground at G. winding of relay 212, and contact springs 227 and 228 to battery B Relay 212 locks itself in an obvious manner by closing contact springs 221 and 222; and also, by separating contact springs 223 and 224, opens the circuit of the line drop 165.

Relay 211, at each dei nergization, breaks the circuit of the line relay 250 of the connector F. In response to thesc interruptions of its circuit, the line relay 250 dcencrgizes a corresponding number of times sending at each dei nergization an impulse to the slow acting relay 252 and the vertical magnet 255 in series, side switch wiper 2M being, in its first position. In response to these impulses the vertical magnet operates to raise the switch shaft until the wipers 2fi'() 271 and 272 stand opposite the horizontal lcvel containing the line contacts of substation A. The relay 252, bcing slow acting retains its armature attracted during the series of impulses and thereby maintains an energizing circuit for the private magnet 259. At the end of the series of impulses the relay 252 and the private magnet dci uergizc, the latter controlling the side switch wipers in the usual manner to advance them to thcir sci, ond position.

The operator may now manipulate the calling device S in accordance with the filial digit of the desired number, resultin as before in doinergizations of the A. relay 160. The consequent interruptions are repcatcd as before described until they afieet the line relay 250 of the connector F, which now. side switch wiper 261 being in its sec- 1 ond position sends impulses to the relay 252 in series with the rotary magnet 2 56. In response to these impulses the rotary magnet operates to rotate the switch shaft until the Wipers 27(L 271, and 272 are brought to rest upon bank contacts 273, 274, and 275, which are the contacts associated with the line of substation A. The private magnetis again oontrolled by the relay 252 responsive to the final series of impulses to advance the side switch wipers to their thirdposition.

As side switch wiper 2G3 comes into its third position, a circuit is com dated from ground at G by way of wiper 2 1 and bank contact 2H to the holding winding 330 of line switch C. Upon energizing, the holding winding operates the cut-off armature 331, whereby the line conductors of substation A are i'lisconnected from their connections in line switch C. iround from Gr also ex- 27-l in the banks of other connectors of the group, thereby making the line busy to other calls. By the advance of side switch wipers 261 and 262 to their third positions the connection is completed to the called line. By the advance of side switch wiper 264 to its third position a circuit is completed for the ringing relay 260, which is operated intermittently thereafter by the interrupter I to signal the subscriber at substation A. \Vhen the called subscriber removes his receiver in response to the ringing of his hell a circuit is completed in the well known manner for the double wound back bridge relay 253 (ringing relay 260 being tem- 1N -arily dei nergized) which relay, upon energiizing, reverses the incoming line conductors (of no particular consequence) and also completes a circuit for the ring cut-oil relay 258. The ring cut-off relay, upon attracting its armature. locks itself to ground at G" and at the same time opens the circuit of the ringing relay 260.

At the originating exchange, when the operator has completed the dialing of the required number she may now restore the calling device key K, thereby making the calling dc vice S available for use in other connections. Assuming that the subscriber at substation A has replaced his receiver after placing his call, the operator will now operate the ringing key K to again call him to the telephone. In response to the ringinn of his bell the calling subscriber at sub station A may now remove his receiver from the hook, when the. required connection will have been completed. Current for the trans tends to multiple contacts similar to contact the side mitter at the calling substation is supplied through the windings f the supervisory relay 21 of the cord circuit 1 while current for the transmitter of the called substation is supplied through the ,windings of the double Wound back bridge relay 253 of the connector F. The complete path for voice currents has been drawn in heavy'lines and should be apparent without further explanation. a

. When the conversation is finished both subscribers will replace their receivers.

pon replacing the receiver at substation A the relay 21 is deenergizcd, thereby lighting the supervisory lamp L. By this means the operator is informed that the conversation is at an end, whereupon she may remove both plugsof cord circuit P from the jacks. The removal of the plug from jack removes ground from cut-ofi relay 15, whereby the individual apparatus associated with substation A is restored to normal condition. The removal of the plug from jack J breaks the circuit of relay 31. Relay -31, upon deenergizing, breaks the locking circuit of relay 32, which relay, upon deenergi zing in turn, disconnectsthe generator 48 from the circuit of the A. C. relay 160 (Fig. 2). The relay 160 thereupon retracts its armature and breaks the circuit of relays 210 and 211 of repeater E. gization of relay 211 the circuit of the line relay 250 of the connector F is broken, whereupon all the automatic switches are restored to normal position in the well known manner.

If the line of substation A had been busy when called, the connector H would have operated after the final seriesof impulses to connect a lead from the busy signaling machine Q with one side of the calling line, switch? wipers being held in the second position for this purpose and to prevent connection with the called line. Upon receiving the busy signal. the operator at thedistant exchange removes the plug from jack J whereupon the apparatus is restored to normal as hereinbefore described.

The toll line 51 52 is adapted for regu ar manual operation as well as for automatic operation and I will now describe in a cursory manner how this is accomplished. Assuming that the operator at the originating exchange desires to establish a connection manually with the aid ofthe operator at the distant exchange. she will use the same cord circuit as before, but instead of throwing the calling device key K she will operate the ringing'key K in her cord circuit.

a result, the drop 165 at the distantex change is actuated, thereby signaling the operator there stationed, who will respond by inserting the plug of a cord circuit simihr tccord circuit P in jack J. The oper- By the deenerother end. Morse telegraph circuit shown, more modernators at the two exchanges may now converse jack and the cut-off relay is disabled, all as has been described. It is important to note in this connection that While the operator at the No. 2' exchange cannot interfere with automatic connections established by operators in the No. 1 exchange to the extent of disconnecting such connections, she is enabled, nevertheless, to supervise such a connection by; simply disregarding the busy test and plugging into the jack. This feature is often a valuable one.

Referring now to the telegraph equipment, the signaling impulses transmitted over. the simplex circuit are of comparatively low frequency, if such term may be used with reference to interruptions 9 direct current, and the barriers located in the branches at each end effectually revent the shuntingof such impulses from t eir proper path. It will be seen, therefore, that teleniatic switches may occur simultaneously.

While I have shown and described in the foregoing a certain s ecific embodiment of my invention it will e evident to persons skilled in the art that may be made without further invention.- For example, the exchange to which substation A is connected might be an automatic exchange, whence it would naturally follow that the toll line 51-52 should be ada ted for automatic Such adaptation may be made by simply duplicating the equipment at each end at the Also, instead of the simple and eflicient systems may be used, such as well known duplex or quadruplex systems. Or, if desired, apparatus other than telegraph equipment may be operated, care be:

ing taken to include suflicient impedance ateach end of the circuit to prevent shunting of the alternating current from the auto matic switch operating circuit.

In view of these considerations I do not wish to limit my invention to the articular embodiment shown but desire rat er to include and have all forms and mbdificationsthereof which may come within the scope of the appended claims. i

What I claim as my invention is:

1. In a telephone system, a line connecting many modifications operation in both (liIBCtIOHS,

protected by Letters Patent two exchanges, means including said line and an automatic switch at one exchange for connecting subscribers lines in the two exchanges, a telegraph circuit superimposed on said line, a branch of said circuit at one end containin a condenser and a controlling relay for sai switch, and a branch of said circuit at the other end containing a condenser and a source of alternating current for operating said controllin relay.

2. In a telephone system, aIine connecting two exchanges, means including said line and an automatic switch at one exchange for connecting subscribers lines in the two exchanges, a telegraph circuit superi xn osed on said line, a controlling circuit or said switch includin the superimposed ortion of said telegrap circuit, a source 0 alternating current in said controlling circuit at one end, and a relay in said controlling circuit at the other end.

3. In a telephone system, a line connecting two exchanges, means including said line and an automatic switch at one exchange for connecting subscribers lines in the two ex-v changes, a telegraph circuit superim )osed on said line, a controlling circuit or said switch includin the superimposed portion of said telegrap circuit, a source of alternating current in said controlling circuit at one end, a relay in said controlling circuit at the other end, and an electrical tuning device in said controlling circuit whereby the said controlling circuit is made resonant to the frequency of said alternating current source.

V 4. In a combined telephone and telegraph system, means including a toll line and an automatic switch for establishing telephone connections, a direct current telegraph circuit, a controlling circuit for said switch, said circuits having a common portion superimposed on said toll line, a source of alternating current in said controlling circuit at one end, and a controlling relay for said switch in said controlling circuit at the other end.

5. In a combined telephone and telegraph system, means including a toll line and an automatic switch for establishing telephone connections, a direct current telegraph circuit. a controlling circuit for said switch, said circuits having a common portion superimposed on said toll line, a source of alternating current in said controlling circuit at one end. controlling relay for said switch in said controlling circuit at the other cud. an electrically tuned barrier impervious to dircct current in said controlling circuit at cach cud, and a device offering high impedance to alternating current in said telegraph circuit at each end.

6. In a telephone system, a line conncctlng two exchanges, means including said line and an automatic switch at one exchange for connecting subscribers lines in the two exchanges, a telephone for each line, said switch also for establishing a talking circuit between telephones of the connected lines, a telegraph circuit superimposed on said lines so as to include conductors in both sides of a section of the talking circuit in parallel, a branch of said circuit at one and containing a condenser and a controlling relay for said switch, and a branch of said circuit at the other end containing a condenser and a source of alternating current for operating said controlling relay.

7. In a telephone system, a line connecting two exchanges, means including said line and an automatic switch at one exchange for connecting subscribers lines in the two exchanges, a telephone for each line, said switch also for establishing a talking circuit between telephones of the connected lines, a telegraph circuit superimposed on said lines so as to include conductors in both sides of a section of the talking circuit in parallel, a controlling circuit for said switch including the superimposed portion of said telegraph circuit, a source of alternating current, in said controlling circuit at one end, and a relay in said controlling circuit at the other end.

8. In a telephone system, a line connecting two exchanges, means including said line and an automatic switch at one exchange for connecting subscribers lines in the two exchanges, a telephone for each. line,- said switch also for establishing a talking circuit between telephones of the connected lines, a telegraph circuit superimposed on said lines so as to include conductors in both sides of a section of the talking circuit. in parallel, a controlling circuit for said switch including the superimposed portion of said telegraph circuit, a source of alternating current in said controlling circuit at one end, a relay in said controlling circuit at the other end, and an electrical tuning device in said controlling circuit whereby the said controlling circuit is made resonant to the frequency of said alternating current source.

9. In combination, a telephone circuit for talking between two telephones, a second circuit for tclegraphing purposes, and a third circuit for controlling the continuity of said talking circuit, said second and third circuits superimposed on said talking circuit, means whereby current may flow over all of said circuits simultaneously.

10. In combination, a telephone circuit for talking between two telephones, a scrond circuit for telegraphing purposes, a third circuit for controlling the continuit of said talking circuit, said second and t ird circuits superimposed on said talking circuit, means whereby current may flow over all of said circuits simultaneously, and means for preventing interference between said circuits.

11. In combination, a telephone circuit for talking between two telephones, a second circuit for telcgmphing purposes, a third circuit for controlling the continuity of said talking circuit, said second and third circuits superimposed on said talking circuit so as to include conductors in both sides of a section of the talking line in parallel, means whereby current may flow over all of said circuits simultaneously, and means for preventing interference between said circuits.

Signed by me at Chicago, Cook county, State of Illinois, this 19th day of April, 1916,

ARTHUR BESSEY SMITH. 

